The present invention relates to padlocks and relates more particularly to a concealed shackle padlock having shackle protecting tubes for protecting the shackle against bolt cutters, hacksaws and jimmying tools.
Various padlocks are known and widely used for the advantage of removable. A conventional padlock, as illustrated in FIG. 1, has a shackle that can be passed through a staple or link and then secured. Because the shackle is exposed to the outside, a conventional padlock may be opened by an intruder with a bolt cutter, hacksaw or jimmying tool. In order to provide added protection, there is disclosed a padlock with shackle protecting plates. This structure of a padlock, as illustrated in FIGS. 2 and 3, has two shackle protecting plates on the top of the casing at two opposite ends thereof. One shackle protecting plate has a substantially U-shaped cross section surrounding the fixed end of the shackle. The other shackle protecting plate has a substantially L-shaped cross section for protecting the free end of the shackle. This structure of a padlock is complicated and expensive to manufacture. When opening or closing this padlock, the arched middle part of the shackle must be lifted over the top edge of the U-shaped shackle protecting plate so that the free end of the shackle can be rotated outwards or inwards relative to the casing of the padlock. Another disadvantage of this structure of a padlock is that the L-shaped shackle protecting plate which is provided for protecting the fee end of the shackle can not protect against jimmying tools. The arrangement of this L-shaped shackle protecting plate limits the rotary range of the shackle within a fixed angle (see FIG. 3), i.e., the free end of the shackle is prohibited from rotating through a 360 angle. Furthermore, the arched middle part of the shackle may be exposed to the outside when locked on chains (see FIG. 4), and the padlock may be opened with a bolt cutter or hacksaw.